I saw a guy do this the other day.
While fueling my TDI, a man and his kid were fueling at a nearby pump. While talking to his kid, the guy actually pointed at my car (obviously saying something like "Look at that guy putting DIESEL in his car"...
)
They were paying so much attention to me that the guy forgot to pull the nozzle out, and he drove off with it.
It didn't break off, but it "snapped back" quite loudly, and he stopped and said "Oh, damn!" before screeching off.
Probably embarassed the hell out of him, in front of his kid too.